# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.


# This module is shared by multiple linkers; use include blocker.
include_guard()

block(SCOPE_FOR POLICIES)
cmake_policy(SET CMP0054 NEW)
cmake_policy(SET CMP0140 NEW)

function(__linker_gnu lang)
  # define flags for linker depfile generation
  set(CMAKE_${lang}_LINKER_DEPFILE_FLAGS "LINKER:--dependency-file,<DEP_FILE>")
  set(CMAKE_${lang}_LINKER_DEPFILE_FORMAT gcc)

    if(NOT DEFINED CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED)
      ## Ensure ninja tool is recent enough...
      if(CMAKE_GENERATOR MATCHES "^Ninja")
        # Ninja 1.10 or upper is required
        execute_process(COMMAND "${CMAKE_MAKE_PROGRAM}" --version
                        OUTPUT_VARIABLE _ninja_version
                        ERROR_VARIABLE _ninja_version)
        if (_ninja_version MATCHES "[0-9]+(\\.[0-9]+)*")
          set (_ninja_version "${CMAKE_MATCH_0}")
        endif()
        if (_ninja_version VERSION_LESS "1.10")
          set(CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED FALSE)
        endif()
      endif()

      if (NOT DEFINED CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED)
        ## check if this feature is supported by the linker
        if (CMAKE_${lang}_COMPILER_LINKER AND CMAKE_${lang}_COMPILER_LINKER_ID MATCHES "GNU|LLD")
          execute_process(COMMAND "${CMAKE_${lang}_COMPILER_LINKER}" --help
                          OUTPUT_VARIABLE _linker_capabilities
                          ERROR_VARIABLE _linker_capabilities)
          if(_linker_capabilities MATCHES "--dependency-file")
            set(CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED TRUE)
          else()
            set(CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED FALSE)
          endif()
        else()
          set(CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED FALSE)
        endif()
      endif()
    endif()
    if (CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED)
      set(CMAKE_${lang}_LINK_DEPENDS_USE_LINKER TRUE)
    else()
      set(CMAKE_${lang}_LINK_DEPENDS_USE_LINKER FALSE)
    endif()

    # Due to GNU binutils ld bug when LTO is enabled (see GNU bug
    # `30568 <https://sourceware.org/bugzilla/show_bug.cgi?id=30568>`_),
    # deactivate this feature if the version is less than 2.41.
    if (CMAKE_${lang}_COMPILER_LINKER_ID
        AND CMAKE_${lang}_COMPILER_LINKER_ID STREQUAL "GNU"
        AND CMAKE_${lang}_COMPILER_LINKER_VERSION VERSION_LESS "2.41")
      set(CMAKE_${lang}_LINK_DEPENDS_USE_LINKER FALSE)
    endif()

  return(PROPAGATE CMAKE_${lang}_LINKER_DEPFILE_FLAGS
                   CMAKE_${lang}_LINKER_DEPFILE_FORMAT
                   CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED
                   CMAKE_${lang}_LINK_DEPENDS_USE_LINKER)
endfunction()

endblock()
